Sample function delete related attachments (created by ACF) when deleting a post

debug.log

[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 189
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 190
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 191
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 192
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 193
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 194
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 195
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 196
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete gallery attachment id 197
[06-Jan-2024 16:29:06 UTC] INFO: Delete product 188: delete video attachment id 235
[06-Jan-2024 16:29:06 UTC] INFO: No attachment found in database

prune-acf-fields-on-delete-post.php

<?php
/**
 * Case is very useful if you have media/file field and set it 'Uploaded to post' feature only
 * Disclarm: You should be backup before running a script. I just place and test with sample from one of our projects.
 * Steps: (1) Delete a post. (2) Find post in Trash and delete it permanently
 *
 * @package codetot-labs
 * @author codetot
 * @since 0.0.2
 **
**/ 
add_action('before_delete_post', 'codetot_delete_post_attachments');
function codetot_delete_post_attachments($post_id) {
	global $wpdb;
	$post_type = get_post_type( $post_id );

	if ($post_type !== 'event') { // Replace with your own post_type key
		return;
	}

	// Delete galley ids
	$gallery_ids = get_field('gallery', $post_id);
	if ( !empty($gallery_ids) ) {
		foreach ($gallery_ids as $gallery_image_id) {
			error_log('INFO: Delete post ' . $post_id . ': delete gallery attachment id ' . $gallery_image_id );
			wp_delete_attachment($gallery_image_id, true);
		}
		delete_field('gallery', $post_id);
	}

	// Delete video id
	$video_id = get_field('video', $post_id);
	if ( !empty($video_id) ) {
		error_log('INFO: Delete post ' . $post_id . ': delete video attachment id ' . $video_id );
		wp_delete_attachment($video_id, true);
		delete_field('video', $post_id);
	}

	$attachment_ids = $wpdb->get_col("SELECT ID FROM {$wpdb->posts} WHERE post_parent = $post_id AND post_type = 'attachment'");

	foreach ( $attachment_ids as $attachment_id ) {
		error_log('INFO: Delete post ' . $post_id . ': delete attachment id ' . $attachment_id );
		wp_delete_attachment($attachment_id, true);
	}

	$post_thumbnail_id = has_post_thumbnail( $post_id ) ? get_post_thumbnail_id( $post_id ) : null;

	if ( !empty( $post_thumbnail_id ) ) {
		error_log('INFO: Delete product ' . $post_id . ': delete post thumbnail attachment id ' . $post_thumbnail_id );
		wp_delete_attachment($post_thumbnail_id, true);
	}
}